[Hereditary familial non polypoid colorectal cancer].

The most common form of hereditary CRC is hereditary non-polyposis colorectal cancer (HNPCC), several mutator genes have been identified in this syndrome. The molecular genetic discoveries are providing news insights into the pathogenesis of CRC. The CRC in Lynch syndrome shows microsatellite instability and it also shows a special histology now referred to as an undifferentiated medullary or solid cribriform carcinoma. This histology is uncommon in various populations. In addition CRC in HNPCC shows an excess of mucoid features as well as peritumoral lymphocyte infiltration and Crohn-like reaction. It is very important to make a diagnosis based on the natural history features of a particular cancer syndrome in combination with a well orchestrated family history. We report the case of a 44 year old man with colon cancer and adenomatous polyps, without family history of adenomatous polyps but with familial antecedent of colon cancer in his father, with a suspicion of Lynch syndrome.